1. Field
Embodiments described generally relate to urea mixtures. More particularly, such embodiments relate to urea mixtures that include urea, a urea-aldehyde resin, a liquid medium, and a sugar and methods for making and using same.
2. Description of the Related Art
Typical adhesives used in the production of lignocellulose composite products such as medium density fiberboard, plywood, and particle board include amino-formaldehyde resins such as urea-formaldehyde (“UF”), melamine-formaldehyde (“MF”), and melamine-urea-formaldehyde (“MUF”) resins. While these resins produce lignocellulose composite products having desirable properties, such as strength, these resins can release formaldehyde into the environment during the production of the resin, during the curing of the resin, and during recycling or incineration of the composite product at the end of its lifecycle. The release of formaldehyde is undesirable due to its environmental and health effects.
Various techniques have been used to reduce the amount of formaldehyde released from amino-formaldehyde resins. One such technique is the addition of formaldehyde scavengers, e.g., urea, to the resins. Urea is typically used in solution form, but solutions with high concentrations of urea, e.g., 40% aqueous urea, are susceptible to having the urea precipitate out of solution. In the past, salts have been used to inhibit this precipitation. Salt, however, can have drawbacks such as causing corrosion and forming build-up in the processing equipment.
There is a need, therefore, for improved urea solutions that are stable for extended periods of time and can be used as formaldehyde scavengers.